Liquid material discharge device for discharging a fixed amount of liquid material

Abstract

A discharge device capable of suppressing pressure fluctuation of a compressed gas supplied to a container in which a liquid material is stored. The device includes a storage container in which a liquid material is stored; a discharge port through which the liquid material is discharged; a pressure control valve that adjusts a pressure of a compressed gas supplied from an external compressed gas source to a desired level; a discharge valve that establishes or cuts off communication between the pressure control valve and the storage container; a control device that controls operation of the discharge valve; a first flow line connecting the pressure control valve and the discharge valve; and a second flow line connecting the discharge valve and the storage container. The device further includes a third flow line branched from the first flow line, and a leak mechanism connected to the third flow line.

The invention claimed is: 
     
       1. A liquid material discharge device comprising:
 a storage container in which a liquid material is stored; 
 a discharge port through which the liquid material is discharged; 
 a pressure control valve that adjusts a pressure of a compressed gas supplied from an external compressed gas source to a setting value by raising and lowering the pressure of the compressed gas supplied from the external compressed gas source; 
 a discharge valve that establishes or cuts off communication between the pressure control valve and the storage container, the discharge valve comprising an inlet port, an outlet port and an exhaust port; 
 a controller that controls operation of the discharge valve such that during a discharge operation, the inlet port and the outlet port are communicated with each other, and at the end of the discharge operation, the communication between the inlet port and the outlet port is cut off, and the outlet port is communicated with the exhaust port to vent the compressed gas inside the storage container through the exhaust port; 
 a first flow line connecting the pressure control valve and the inlet port of the discharge valve, the pressure control valve supplies the compressed gas and the pressure of the compressed gas is adjusted in the first flow line between the pressure control valve and the discharge valve; and 
 a second flow line connecting the outlet port of the discharge valve and the storage container, 
 wherein the liquid material discharge device further comprises a third flow line branched from the first flow line upstream of the inlet port of the discharge valve and downstream of the pressure control valve, and a leak valve or a leak orifice provided on the third flow line, 
 the leak valve or the leak orifice is configured to leak a part of the compressed gas the pressure of which is adjusted by the pressure control valve so as to suppress pressure fluctuations in the second flow line and the storage container, and 
 during the discharge operation, the leak valve or leak orifice is configured to continuously leak an amount of the compressed gas which is supplied through the first flow line and the third flow line from the pressure control valve and which is necessary to keep the pressure of the compressed gas in the first flow line lower than the setting value such that the pressure control valve continues to perform a supply operation of the compressed gas during the discharge operation. 
 
     
     
       2. The liquid material discharge device according to  claim 1 , wherein a fixed amount of liquid material is discharged through the discharge port by supplying the compressed gas to the storage container. 
     
     
       3. The liquid material discharge device according to  claim 1 , wherein the leak valve or the leak orifice is constituted by one orifice. 
     
     
       4. The liquid material discharge device according to  claim 3 , further comprising an open-close valve disposed downstream or upstream of the one orifice, wherein the one orifice and the open-close valve constitute an orifice open-close mechanism. 
     
     
       5. The liquid material discharge device according to  claim 4 , wherein the open-close valve is an automatic open-close valve that is opened and closed by the controller. 
     
     
       6. The liquid material discharge device according to  claim 4 , wherein the liquid material discharge device includes the orifice open-close mechanism in plural sets connected in parallel. 
     
     
       7. The liquid material discharge device according to  claim 6 , wherein the plural sets of orifice open-close mechanisms include a first orifice open-close mechanism, and a second orifice open-close mechanism providing a different flow rate from that provided by the first orifice open-close mechanism. 
     
     
       8. The liquid material discharge device according to  claim 1 , wherein the leak valve or the leak orifice includes a flow control valve providing a flow rate that is controllable by the controller. 
     
     
       9. The liquid material discharge device according to  claim 1 , wherein the pressure control valve is an electropneumatic regulator of which operation is controlled by the controller. 
     
     
       10. The liquid material discharge device according to  claim 1 , further comprising a casing that contains the pressure control valve, the discharge valve, the leak valve or leak orifice, and the controller,
 wherein the casing includes a first joint to which a flow line in communication with the compressed gas source is detachably attached, and a second joint to which a flow line in communication with the discharge valve is detachably attached. 
 
     
     
       11. The liquid material discharge device according to  claim 1 , further comprising a load-increasing vacuum connected to a terminal end of the third flow line. 
     
     
       12. The liquid material discharge device according to  claim 1 , further comprising a vacuum for the discharge valve, the vacuum generating a negative pressure in a flow passage in the discharge valve. 
     
     
       13. The liquid material discharge device according to  claim 1 , further comprising a buffer tank disposed in the first flow line. 
     
     
       14. An application device comprising the liquid material discharge device according to  claim 1 , a worktable on which a workpiece is placed, a moving device that moves the discharge port and the workpiece relative to each other, and the external compressed gas source that supplies the compressed gas to the liquid material discharge device.